1. Technical Area
The invention relates to data storage devices such as magnetic bubble memories that do not allow direct access to a desired stored word and, more specifically, to a control arrangement for coordinating data operations respective of such devices.
2. Art Discussion
Control arrangements for data storage devices that do not provide for direct word access serve in coordinating the multiple basic storage operations that are involved in executing the data storage requests initiated by an associated system. For example, with a magnetic bubble storage device, a request for the data word at a specified storage address typically involves a series of basic operations to advance, replicate and detect the stored information that is to be accessed. Circulation of stored information in minor loops is typically required to advance data to a site where a replication occurs to place corresponding data on a channel at which a read operation may be performed. Finally, the read operation is effected when the data is shifted to a detection site on the channel.
To provide for system interaction with such a storage device that requires involved sequences of operation customized to each request, a controller is often used which includes discrete logic designed specifically for supplying control signals that serve to coordinate basic storage maneuvers.
A further approach uses a microprocessor to control the basic operations but a high performance microprocessor typically becomes necessary to generate the control signals at rates sufficient to utilize the storage efficiently. Furthermore, the microprocessor usually is dedicated to the single purpose of storage control.